Switch testing apparatus

ABSTRACT

A method for testing a thermal-responsive switch which utilizes liquidized nitrogen for lowering the switch to its operational level.

United States Patent 1191 Hardesty Aug. 14, 1973 [54] SWITCH TESTINGAPPARATUS 3,245,248 4/1966 Ritter .Q 73/1 F [76] Inventor: Donald L.Hardest), 900 Olmstead Ave., Evansville, Ind. 47711 221 Filed: July 6,1971 21 Appl. No: 159,931

[58] Field of Search 324/28; 73/1 F, 15; 337/99, 306; 62/64, 373, 125

[56] References Cited UNITED STATES PATENTS 2,526,713 10/1950 Underwood73/1 F Primary Examiner-Eli Lieberman Attorney-Warren D. Flackbert [57]ABSTRACT A method for testing a thermal-responsive switch which utilizesliquidized nitrogen for lowering the switch to its operational level.

2 Claims, 1 Drawing Figure rAnzmznmm ms 3.751083 INVENTOR 00mm 0 4.Mqnoes rr BY 2% HQ/Ml ATTORNEY SWITCH TESTING APPARATUS As is known, thetesting of refrigerator and/or freezers at the manufacturing plant hasbeen a rather time consuming operation, in that it has been necessary tooperate the product until functional temperatures are achieved. In otherwords, a selective number of units are tested, being operated until theswitch limits are reached and then it is determined whether or not therefrigerator and/or freezer is acceptable. A big drawback from thepreceding, aside from time, was the fact that only a limited number ofproduction units could be tested, because of either facility spaceand/or production rate. Accordingly, it has become necessary, forconsumer relations to furnish a workable product, where the pro-testingthereof can be readily accomplished and at a minimal cost.

The invention accomplishes all of the preceding objectives, i.e. rapidand limitless product testing and a savings in time and testing expense.Briefly, the invention utilizes a cryogenic gas, such as liquidizednitrogen, which is sprayed onto the appropriate switch in therefrigeration mechanism to reduce the temperature thereof to anoperating level. Such may be accomplished through the use, typically, ofa hand-controlled gun to spray the temperature responsive switch. Assoon as the desired temperature level is achieved, the unit can betested and determined whether or not it is satisfactory for sale.

The invention can be better understood from the following description,taken in conjunction with the ac-- companying drawing, wherein thesingle FIGURE thereof shows the components employed in the performanceof the invention.

For the purposes of promoting a better understanding of the principlesof the invention, reference will now be made to the embodimentillustrated in the drawing and specific language will be used todescribe the same. It will nevertheless be understood that no limitationof the scope of the invention is thereby intended, such alterations andfurther modifications in the illustrated method, and such furtherapplications of the principles of the invention being contemplated aswould norm ally occur to one skilled in the art to which the inventionrelates.

Referring now to the figure, the method of the invention comprises theuse of a source of liquidized nitrogen 12, a conventional regulator 14,and a spray gun to for achieving the direct depositing; of theliquidized nitrogen onto a thermal-responsive switch 17 within arefrigerator and/or freezer 19. The process may be manually accomplishedor, if desired, carried out through the use of a fixed equipment set-up.In use, the liquidized nitrogen is sprayed onto the switch, lowering thetemperature of the switch to an operating level to permit operation ofthe refrigerator and/or freezer as after many hours of use.

In other words, the invention saves a considerable amount of time forlowering the temperature of the unit so that testing can be quicklyaccomplished. The switch testing is readily available for each productunit, serving to satisfy the manufacturer of the proper assembly of theproduct and readily reducing failures which commonly occur in a finishedproduct.

While the use of liquidized nitrogen has been emphasized, othercryogenic gases may be employed, such as argon, oxygen, helium orhydrogen; however, nitrogen is most plentiful and is not expensive orpotentially dangerous.

Thus, from the preceding, it should become apparent that the use ofliquidized nitrogen effectively serves as a testing vehicle and,accordingly, represents a valuable contribution to product quality. Thedescription hereabove should be considered illustrative and not aslimiting the scope of the following claims:

I claim:

1. Apparatus for testing the operation of a thermostat mounted in afreezer or refrigerator comprising a source of a liquified nitrogen gas,means for pressurizing said source, an insulated flexible hose connectedbetween said source and a gun, said gun including a nozzle for thedelivery of a fluid stream therethrough and a solenoid operated valvefor controlling the flow of said liquified gas through said hose to saidnozzle, and a trigger for actuating the solenoid to open said valve.

2. The apparatus of claim 1 where a timer circuit is provided forclosing said solenoid a predetermined time after operation of saidtrigger.

1. Apparatus for testing the operation of a thermostat mounted in afreezer or refrigerator comprising a source of a liquified nitrogen gas,means for pressurizing said source, an insulated flexible hose connectedbetween said source and a gun, said gun including a nozzle for thedelivery of a fluid stream therethrough and a solenoid operated valvefor controlling the flow of said liquified gas through said hose to saidnozzle, and a trigger for actuating the solenoid to open said valve. 2.The apparatus of claim 1 where a timer circuit is provided for closingsaid solenoid a predetermined time after operation of said trigger.